CVE-2009-1372 in ClamAV
Summary
by MITRE
Stack-based buffer overflow in the cli_url_canon function in libclamav/phishcheck.c in ClamAV before 0.95.1 allows remote attackers to cause a denial of service (application crash) and possibly execute arbitrary code via a crafted URL.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 08/09/2021
The vulnerability identified as CVE-2009-1372 represents a critical stack-based buffer overflow flaw within the ClamAV antivirus software suite, specifically affecting versions prior to 0.95.1. This issue resides in the cli_url_canon function located in the libclamav/phishcheck.c source file, which is responsible for URL canonicalization and phishing detection capabilities. The flaw manifests when processing malformed or crafted URLs that exceed the allocated buffer space, creating a condition where attacker-controlled data can overwrite adjacent stack memory locations. This vulnerability operates at the application layer and specifically targets the phishing detection module that ClamAV employs to identify potentially malicious web addresses.
The technical exploitation of this buffer overflow occurs through a carefully constructed URL that triggers the cli_url_canon function to write data beyond the confines of its intended buffer allocation. When ClamAV processes such a malformed URL, the function fails to properly validate input length before copying data to the stack buffer, resulting in memory corruption that can lead to unpredictable behavior. The stack-based nature of this vulnerability means that the overflow can overwrite return addresses, saved registers, and other critical stack frame data, potentially allowing remote attackers to redirect program execution flow. According to CWE-121, this represents a classic stack-based buffer overflow vulnerability where insufficient bounds checking enables attackers to overwrite adjacent memory locations.
The operational impact of CVE-2009-1372 extends beyond simple denial of service to potentially enabling remote code execution in vulnerable environments. While the primary effect manifests as application crashes and service disruption, the underlying memory corruption creates opportunities for sophisticated exploitation techniques. Attackers can craft URLs that, when processed by ClamAV, cause the application to crash or potentially execute arbitrary code with the privileges of the ClamAV process. This vulnerability is particularly concerning in environments where ClamAV is deployed as a network-based security solution, as it could be exploited through web traffic processing or email scanning functions. The ATT&CK framework categorizes this type of vulnerability under T1203 - Exploitation for Client Execution, as it represents an attack vector that leverages application-level flaws to achieve unauthorized code execution.
Mitigation strategies for CVE-2009-1372 primarily focus on immediate software updates and deployment of patched versions of ClamAV. Organizations should prioritize upgrading to ClamAV version 0.95.1 or later, which contains the necessary fixes to prevent the buffer overflow condition in the cli_url_canon function. Additionally, network administrators should implement URL filtering and content inspection mechanisms to prevent potentially malicious URLs from reaching ClamAV scanning processes. The vulnerability highlights the importance of input validation and bounds checking in security software, particularly in modules that process untrusted data such as URLs. Security teams should also consider implementing monitoring and alerting for unusual application crashes or memory access patterns that might indicate exploitation attempts. Organizations with legacy systems or restricted update capabilities should consider implementing network segmentation and access controls to limit the potential impact of successful exploitation attempts.